Earth System Science Center and Department of Atmospheric Science at The University of Alabama in Huntsville

Past Seminars – Spring 2015

seminarprogram

Location:
National Space Science and Technology Center
320 Sparkman Drive,
Huntsville, AL 35805,
Conference Room 4065

Days/Time:
Wednesdays at 12:45 p.m. – 1:45 p.m. —
UNLESS OTHERWISE NOTED.

Please contact Dr. John Mecikalski (961-7046) or Ms. Lynn B. Bell (961-7729) concerning any questions, suggestions, or contributions relative to the seminar schedule.


Wednesday, January 14th

Brenda Dolan (Colorado State University)
‘Kinematic and Microphysical Observations of MC3E Convection’

A network of scanning radars and disdrometers is used to characterize storm kinematics and microphysics associated with convection occurring during the Mid-latitude Continental Convective Clouds Experiment (MC3E). Multiple-Doppler based radar retrievals of vertical wind speed compare to those from profiler-based to within 1 ms-1, although some underrepresentation of downdrafts is noted. Comparisons of a radar-based multi-wavelength hydrometeor identification (HID) and surface disdrometers reveal changes in the drop size distributions observed at the surface reflect microphysical process forming the precipitation. For example, the formation of so-called big drops (> 5 mm in diameter) is most likely associated with melting hail and graupel in convective cores.

These radar observations are compared to statistical composites derived from simulations from the Weather Research Forecasting model with Spectral Bin Microphysics (WRF-SBM) for the 25 April 2011 case of elevated convection. Radar observations and simulated reflectivities and vertical motions are similar, although simulated reflectivity and updraft (downdraft) speed maxima are larger (smaller) than observations. A new method to map model particle bins to radar HID fields allows for evaluating bulk microphysics from complex size- and density-resolved microphysics. The largest difference is WRF-SBM underestimates the amount of ice crystals above 10 km height and also underestimates the amount of drizzle. This is related to the too-weak radar echo in drizzle and ice crystals represented by WRF-SBM. These differences could be attributed to a WRF-SBM bias, the mapping between the model and observations, overlap between hydrometeor categories, and potentially the need for a new HID category called ‘irregular ice’ as well as model improvement.

Visit Coordinator:  Patrick Gatlin (Patrick.Gatlin@nasa.gov)

 


 

ThemisTalk01212015_0466

 

 

 

Wednesday, January 21st

Themis Chronis (University of Alabama in Huntsville)
‘Characteristics of Storms Generating Terrestrial Gamma Rays’

TGFs were discovered only about twenty years ago and many fundamental questions remain unanswered.  How are TGFs produced?  There are currently two competing theories, the acceleration of electrons in large-scale electric fields, and the acceleration at the tips of lightning leaders.  How many TGFs are there?  It’s hotly debated how the distribution extends below the bright TGFs observed from gamma-ray detectors in orbit.  Finally, what types of storms make TGFs?

 

Previous efforts to determine which storms produce TGFs have been severely limited due to the inability (with rare exceptions) of the gamma-ray instruments to locate TGFs.  Typically all that we knew was that TGFs were within 800 km of the nadir of the spacecraft, and typically such large regions contains many storms.  With the larger TGF sample of the Fermi Gamma-ray Burst Monitor and the co-detection of many of those TGFs by ground-based radio networks designed to observe lightning, we now have many TGFs localized to few kilometer accuracy.  Twenty-four of these well-localized TGFs are within range of US NEXRAD weather radars, allowing the identification and detailed study of the encompassing storms.


LauraMyers012815

 

 

 

Wednesday, January 28th

Laura Myers (University of Alabama / CAPS)
Societal Response to Weather Forecasting: Understanding the Public Perception of Weather Information
This presentation will discuss the public’s response to severe weather events.  Focusing on the warning dissemination process, results of studies on multiple severe weather event responses will be presented and discussed to explore how the public perceives weather impacts and how they respond to the warning process.

Visit Coordinator: Elise Schultz


PMarkowski_020415_0282

 

 

 

Wednesday, February 4th

Paul Markowski (Penn State University)
‘How to Make a Tornado: Ideas emerging from decades of theory, simulation, and field observations’

The mechanisms of tornadogenesis within atmospheric convection, particularly supercell thunderstorms, which are responsible for virtually all strong tornadoes, will be examined.  Also discussed will be some of the ideas emerging from the recently completely Second Verification of the Origin of Rotation in Tornadoes Experiment (VORTEX2).  Directions for future research will also be addressed.

Visit Coordinator: Kevin Knupp


 

Wednesday, February 18th

Robert (BJ) Barbre (Jacobs ESSSA Group / MSFC Natural Environments Branch)
Application of Terrestrial Environments in Orion Assessments

This presentation will summarize the Marshall Space Flight Center Natural Environments Terrestrial and Planetary Environments (TPE) Team support of the NASA Orion space vehicle.  The TPE utilizes meteorological data to assess the sensitivities of the vehicle due to the terrestrial environment.  The Orion vehicle, part of the Multi-Purpose Crew Vehicle Program, is designed to carry astronauts beyond low-Earth orbit and is currently undergoing a series of tests including Exploration Test Flight (EFT) – 1.  The presentation will describe examples of TPE support for vehicle design and several tests, as well as support for EFT-1 and planning for upcoming Exploration Missions while emphasizing the importance of accounting for the natural environment’s impact to the vehicle early in the vehicle’s program.

Visit Coordinator: U. Nair


Wednesday, February 25th

Will McCarty (NASA/Goddard Space Flight Center)
Past, Present, and Future Infrared Radiance Assimilation at the
Global Modeling and Assimilation Office

Of the twenty million observations routinely assimilated every day in global models, over 80% are satellite radiances.  Consisting primarily of microwave and infrared sounders in sun-synchronous, polar orbits, it is the constellation of these observations that provides global data coverage and has led to forecasts being comparatively skillful in both the Northern and Southern Hemispheres.  Though these data are fundamental to the global observing system and numerical weather prediction skill, only a small fraction of the total observations available are effectively assimilated.  This is particularly true in the thermal infrared, which accounts for ~65% of actively assimilated observations globally via only four instruments.

This talk will focus in part on the assumptions that result in low yields, including cloud screening and data thinning, and present an explanation of: how these methods work, why they are (or were) necessary, how they have evolved, and how effective they are.  The explanation and quantification of these procedures will help illustrate the roadmap of ongoing efforts to further exploit these observations at the Global Modeling and Assimilation Office (GMAO) at NASA/GSFC.  Specifically, this talk will address the topics of cloud-affected radiance assimilation, intelligent data thinning, the evolution of observation characterization over the modern (1979-onward) era, and how all these things relate to both reanalysis and our real-time, forward processing systems.
Visit Coordinator: Brad Zavodsky


Wednesday, March 4th

Robert Swapp (University of Virginia)
‘My programmatic journey thus far — thoughts, perspectives and insights from the inside.”

In 1987 I had my first international field experience as an undergraduate field assistant on the NASA Amazon Boundary Layer Experiment – 2B (ABLE-2B).  That initial international field experience started me on an intellectual path along which I have grown as a researcher and as leader while crisscrossing with other major NASA field campaigns (e.g. TRACE-A/SAFARI-92, SAFARI-2000 and LBA).  As a Research Professor, I now find myself with another opportunity for intellectual and programmatic growth as a rotating IPA program officer with NASA (Intergovernmental Personnel Act).  The purpose of this session is to share thoughts, insights, and lessons learned gleaned from these somewhat unique experiences that have spanned a continuum of involvement from undergraduate field assistant to program principal investigator to program officer with others who might find such perspectives of personal and professional interest.

Visit Coordinator: Sundar Christopher


 

AThompson_03112015

 

 

 

Wednesday, March 11th

Ann Thompson (NASA/Goddard Space Flight Center)
Strategic Ozonesonde Networks: Insights into Ozone Structure in the UT/LS from SHADOZ (1998-) and SEACIONS (2013)

Ozonesonde data support satellite validation, model assimilation and evaluation as well as studies of atmospheric dynamics.  Strategic ozonesonde networks coordinate and schedule launches in a fixed region to answer specific questions (Thompson et al., 2011)*.  We have organized five such networks in the past 15 years.  Most of this talk will focus on the Southern Hemisphere Additional Ozonesondes (SHADOZ; <http://croc.gsfc.nasa.gov/shadoz&gt;) network that consists of a dozen tropical and subtropical stations, with 2-4 launches monthly.  An overview of SHADOZ will be given along with illustrative findings in the upper troposphere and lower stratosphere (UT/LS).  In campaign-class strategic networks daily launches look at ozone short-term variability to complement NASA aircraft missions.  Examples from the 2013 SEACIONS (Southeastern American Consortium for Intensive Ozonesonde Network Study), from the SEAC4RS campaign, will be presented.

 

*  Strategic ozone sounding networks: Review of design and accomplishments, http://dx.doi.org/10.1016/j.atmosenv.2010.05.002. Or Atmos. Environ., 45, 2145-2163, 2011.


Visit Coordinator: Arastoo Pour Biazar


EBruning_031815

 

 

 

Wednesday, March 18th

Eric Bruning (Texas Tech University)
“Meteorology and lightning flash rate, size and energy”

Modern total lightning detection systems can do much more than count lightning flashes and strokes.  One such form of higher-order information provided by these systems is the spatial extent of the lightning channels in the cloud.  The lightning channel’s propagation depends on the distribution of charge in the cloud, and this charge distribution is inextricable from the meteorology of the thunderstorm: the storm’s flow, including at the scales of turbulent eddies, coupled to hydrometeor trajectories, is responsible for the transport and organization of charge.  This talk will review recent work on the lightning flash energy distribution, its possible connection to turbulent eddies, and how the flash size distribution changes in response to stages in the thunderstorm lifecycle and depends on position relative to the mixed-phase updraft.  Also discussed will be a statistical framework relating flash rate, size, channel length, and energy.

Visit Coordinator: Larry Carey


Wednesday, April 8th

Brian Vant-Hull (City University of New York, CUNY)
“Estimating Fine Scale Daytime Surface Air Temperature Anomalies in Manhattan for Health Impacts: a Simple Statistical Model”

The mortality rate during a heat wave is very sensitive to temperature, so variations in temperature between city neighborhoods are of interest to the health community. A series of portable instrument field campaigns during the summers of 2012 and 2013 measured temperature anomalies at the 10-meter scale in a grid across Manhattan, which was supplemented by a set of 10 fixed instruments measuring weather conditions every few minutes during the summer of 2013. The temperature anomalies obtained were regressed against surface features such as elevation, vegetation and building parameters in order to predict temperature anomalies based on surface features alone. The variability among the fixed instruments was regressed against weather variables in order to predict the amplitude of temperature variations based on NWP forecasts. The result is a temperature anomaly map that is scaled based on weather forecasts, providing a simple predictive tool that is easy to implement. It could be merged with a regional model to bring in features such as sea breeze that cannot be captured in our statistical surface feature model.

Visit Coordinator:


Wednesday, April 22nd

Gerald Heymsfield (NASA Goddard)
Deep Convection:  What We Know About Structure, Regional Differences, and Evolution

Understanding the structure of deep convection is important for a number of reasons; for example, vertical transports of mass and moisture, rainfall, and hurricane intensification.  Global measurements of deep convection have mainly been from satellite, such as TRMM that provides an indirect estimate of intensity from the radar reflectivity.  Ground based radars have on the other hand provided detailed measurements of the wind and precipitation structure in convection but mainly in a case study setting.

 

This presentation discusses what we have learned about the structure of deep convection from high-altitude airborne radar measurements from a number of field campaigns mostly in the tropics and subtropics.  The emphasis will be on the updraft structure in the deep convection, as well as what we have learned about the microphysical structure from dual-wavelength measurements.  Finally, several new airborne radars that will improve our understanding of clouds and precipitation will be discussed.


Visit Coordinator: Chris Schultz

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s

Basic HTML is allowed. Your email address will not be published.

Subscribe to this comment feed via RSS

%d bloggers like this: